<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        body {
            padding: 0px;
            margin: 0px;
        }
        div {
            background: red;
            width: 200px;
            height: 200px;
            border: 2px solid blue;
        }

        p {
            width: 100px;
            height: 100px;
            background: green;
            margin-top: 20px;
        }

    </style>
</head>
<body>
<div>
    <div class="c1">
        <p></p>
    </div>
</div>
</body>
</html>